Dr. Val Farmer
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Too Much Of A Good Thing Can Be Fattening

June 18, 2001

I’ve always known why I overeat. I like food. I like the taste of it. When there is a variety of good food - like a buffet, I overeat. It seems I am not alone. Obesity in adults and children has skyrocketed in the Untied States in past thirty years.

Researchers at the University of Buffalo have shown how the variety of foods we eat actually becomes the problem, especially for people are trying to lose or maintain weight.

The variety in our diets keeps us from tiring of the taste of the food, according to psychologists Hollie A. Raynor, M.S., R.D., and Leonard H. Epstein, PhD., of the University of Buffalo. They reviewed more than thirty-nine studies examining dietary variety, energy intake and body composition. They also reviewed nineteen more studies showing what happens to preferences, food intake and pleasure with different foods after we are already "full".

Overeating less likely when eating just one food. Research shows that post-digestive feedback based on calories or food volume doesn’t control appetite. Instead it is the variety of tastes that decreases the feeling of satiation - feeling full. People are more likely to overeat when they are in a situation where they can taste different foods. When eating one food or foods that are similar, the pleasantness of the taste for that particular food decreases, and food intake stops sooner. Our abundant diet offers different varieties of nutrients and prevents nutritional deficiencies - presumably a good thing, a healthy thing. Perhaps all those obese people you see at the "all-you-can-eat" buffets are like compulsive gamblers at a casino. It appears that buffets might be a factor in the increased obesity in America.

Individuals more vulnerable to obesity are actually harmed when exposed to a variety of foods, according to Raynor and Epstein. One theory is that obese people overeat more of one food without tiring of the taste of the food. Actually, however, the opposite is more likely - they are more sensitive of losing taste when exposed to just one food. As a result, they may be more motivated to consume multiple foods when given a large variety of foods so they won't tire of the taste - the danger of meals presented buffet-style.

Too much of a good thing is bad. Most overeating occurs during a meal with several courses (variety spread out over time) with different shapes, flavors, textures and smells with each course. Exposure to novel foods increases the desire to eat in individuals already satiated on other foods. All-you-can-eat buffets have variety and self-regulated time frame for consuming food. Other meals conducive to overeating are holiday and cafeteria meals where a variety of foods are presented simultaneously. When a greater variety of food is available during a meal, it takes longer for satiation to occur for all foods, allowing for a greater intake.

From the review of 58 studies, the researchers found that dietary variety increases food consumption in both humans and animals. "Both people and animals will eat more food when a meal or diet contains greater variety of food, which can eventually cause weight gain. So it isn't surprising that a typical American diet that consists of a large variety in foods like sweets and snacks is linked to being overweight."

In one study, participants were given four courses of food: sausages, bread and butter, chocolate dessert and bananas. Those who had different foods for each course consumed 44 percent more than those who ate the same food for each course. Another study had a similar finding. When different foods are available at the same time during a meal - tuna, roast beef, cheese and egg sandwiches - overeating is more likely than compared to a meal of just one of these foods.

Eating savory foods (cheese and crackers, sausages, bread and butter and potato chips) does not decrease interest in sweets and vice-versa. The same was true for going from hard foods to soft foods.

But, if the foods are similar, then increased eating is less likely, according to Raynor and Epstein. For example, studies that offered participants flavors of yogurt similar in color and texture (cherry, raspberry and strawberry) showed no increases in eating. This result was also found in a study that used three different flavored chocolate candies that were similar in appearance and texture.

Reduce variety for weight loss. Reducing dietary variety of highly tasty, high caloric foods may be useful in treating and preventing obesity, said the researchers. "Limiting these foods in a meal may help reduce the energy intake within a meal, thereby reducing overall intake. Plus, the research shows us that meals composed of foods with similar sensory qualities (taste, shape and color) also may curb overeating during a meal."

To lose weight, think meals with one main food. Boring, but smart.

A low calorie diet that is rich in taste and variety defeats its purpose. Did you ever overeat at a salad bar? One strategy might be to increase the sameness of meats and dairy products at meals while increasing variety in the servings of fruits and vegetables. Also researchers found that smelling a food for five minutes or more before eating ultimately decreases appetite. A cook may not enjoy his or her own cooking as much because of this factor.

Variety is the spice of life, except when it comes to losing weight.